1
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Mountanea OG, Skolia E, Kokotos CG. Photochemical Aerobic Upcycling of Polystyrene Plastics via Synergistic Indirect HAT Catalysis. Chemistry 2024; 30:e202401588. [PMID: 38837489 DOI: 10.1002/chem.202401588] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2024] [Revised: 05/22/2024] [Accepted: 06/02/2024] [Indexed: 06/07/2024]
Abstract
Plastic pollution constitutes an evergrowing urgent environmental problem, since overaccumulation of plastic waste, arising from the immense increase of the production of disposable plastic products, overcame planet's capacity to properly handle them. Chemical upcycling of polystyrene constitutes a convenient method for the conversion of plastic waste into high-added value chemicals, suggesting an attractive perspective in dealing with the environmental crisis. We demonstrate herein a novel, easy-to-perform organocatalytic photoinduced aerobic protocol, which proceeds via synergistic indirect hydrogen atom transfer (HAT) catalysis under LED 390 nm Kessil lamps as the irradiation source. The developed method employs a BrCH2CN-thioxanthone photocatalytic system and was successfully applied to a variety of everyday-life plastic products, leading to the isolation of benzoic acid after simple base-acid work up in yields varying from 23-49 %, while a large-scale experiment was successfully performed, suggesting that the photocatalytic step is susceptible to industrial application.
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Affiliation(s)
- Olga G Mountanea
- Laboratory of Organic Chemistry, Department of Chemistry, National and Kapodistrian University of Athens, Panepistimiopolis, 15771, Athens, Greece
| | - Elpida Skolia
- Laboratory of Organic Chemistry, Department of Chemistry, National and Kapodistrian University of Athens, Panepistimiopolis, 15771, Athens, Greece
| | - Christoforos G Kokotos
- Laboratory of Organic Chemistry, Department of Chemistry, National and Kapodistrian University of Athens, Panepistimiopolis, 15771, Athens, Greece
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2
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Oh S, Stache EE. Recent advances in oxidative degradation of plastics. Chem Soc Rev 2024; 53:7309-7327. [PMID: 38884337 DOI: 10.1039/d4cs00407h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/18/2024]
Abstract
Oxidative degradation is a powerful method to degrade plastics into oligomers and small oxidized products. While thermal energy has been conventionally employed as an external stimulus, recent advances in photochemistry have enabled photocatalytic oxidative degradation of polymers under mild conditions. This tutorial review presents an overview of oxidative degradation, from its earliest examples to emerging strategies. This review briefly discusses the motivation and the development of thermal oxidative degradation of polymers with a focus on underlying mechanisms. Then, we will examine modern studies primarily relevant to catalytic thermal oxidative degradation and photocatalytic oxidative degradation. Lastly, we highlight some unique studies using unconventional approaches for oxidative polymer degradation, such as electrochemistry.
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Affiliation(s)
- Sewon Oh
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, USA
| | - Erin E Stache
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, USA.
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3
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Michelas M, Wimberger L, Boyer C. A General Approach for Photo-Oxidative Degradation of Various Polymers. Macromol Rapid Commun 2024:e2400358. [PMID: 39008823 DOI: 10.1002/marc.202400358] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2024] [Revised: 06/26/2024] [Indexed: 07/17/2024]
Abstract
The escalating demand for plastics has resulted in a surge of plastic waste worldwide, posing a monumental environmental challenge. To address this issue, a versatile photo-oxidative degradation method applicable to seven distinct polymer families is proposed, comprising poly(isobutyl vinyl ether) (PIBVE), poly(2,3-dihydrofuran) (PDHF), poly(vinyl acetate) (PVAc), poly(n-butyl acrylate) (PBA), poly(methyl acrylate) (PMA), poly(vinyl chloride) (PVC), poly(dimethyl acrylamide) (PDMA), poly(ethylene oxide) (PEO), poly(oligo(ethylene glycol) methyl ether acrylate) (PEGMEA), and even poly(methyl methacrylate) (PMMA). This method employs photo-mediated hydrogen atom transfer (HAT) followed by oxidation to promote polymer degradation. This reaction is carried out under aerobic condition in the presence of iron trichloride (FeCl3) as a photocatalyst in combination with low-intensity purple light irradiation. The process can degrade up to 97% of the polymer in less than 3 h. This degradation process can be easily controlled by switching the light off, which allows for precise modulation of the degradation rate, enhancing the effectiveness of the method. Overall, this method provides a sustainable method for degrading various polymer types with low energy input.
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Affiliation(s)
- Maxime Michelas
- School of Chemical Engineering, University of New South Wales, Sydney, NSW, 2052, Australia
| | - Laura Wimberger
- School of Chemical Engineering, University of New South Wales, Sydney, NSW, 2052, Australia
| | - Cyrille Boyer
- School of Chemical Engineering, University of New South Wales, Sydney, NSW, 2052, Australia
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4
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Li J, Ma HP, Zhao G, Huang G, Sun W, Peng C. Plastic Waste Conversion by Leveraging Renewable Photo/Electro-Catalytic Technologies. CHEMSUSCHEM 2024; 17:e202301352. [PMID: 38226954 DOI: 10.1002/cssc.202301352] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2023] [Revised: 12/26/2023] [Accepted: 01/15/2024] [Indexed: 01/17/2024]
Abstract
Plastics have revolutionized our lives; however, the exponential growth of their usage has led to a global crisis. More sustainable strategies are needed to address this dilemma and transform the plastics economy from a linearity to a circular model. Herein, we systematically summarize the recent progress in renewable energy-driven plastic conversion strategies, including photocatalysis, electrocatalysis, and their integration. By introducing the significant works, the design principles, mechanisms, and system regulations, we decipher and compare the various aspects of plastic conversion. These approaches show high reactivity and selectivity under environmentally benign conditions and provide alternative reaction pathways for plastic conversion. Plastic upcycling as a chemical feedstock can yield value-added chemicals and fuels, contributing to the establishment of a sustainable and circular economy. Additionally, several innovations in reaction engineering and system designs are presented. Finally, the challenges and perspectives of sustainable energy-driven plastic conversion technologies are comprehensively discussed.
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Affiliation(s)
- Jianan Li
- School of Chemical Engineering, Dalian University of Technology, Dalian, 116024, P. R. China
- Zhejiang Tiandi Environmental Protection Technology Co., Ltd., Hangzhou, 311121, P. R. China
| | - Hong-Peng Ma
- Key Laboratory of Special Functional and Smart Polymer Materials of Ministry of Industry and Information Technology, Northwestern Polytechnical University, Shaan Xi, 710072, P. R. China
| | - Guoping Zhao
- Zhejiang Tiandi Environmental Protection Technology Co., Ltd., Hangzhou, 311121, P. R. China
| | - Guangfa Huang
- Zhejiang Tiandi Environmental Protection Technology Co., Ltd., Hangzhou, 311121, P. R. China
| | - Wenbo Sun
- School of Resources and Environmental Engineering, Shandong University of Technology, Zibo, 255000, P. R. China
| | - Chong Peng
- School of Chemical Engineering, Dalian University of Technology, Dalian, 116024, P. R. China
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5
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Xu Z, Sun D, Xu J, Yang R, Russell JD, Liu G. Progress and Challenges in Polystyrene Recycling and Upcycling. CHEMSUSCHEM 2024:e202400474. [PMID: 38757556 DOI: 10.1002/cssc.202400474] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2024] [Revised: 05/16/2024] [Accepted: 05/17/2024] [Indexed: 05/18/2024]
Abstract
Polystyrene is a staple plastic in the packaging and insulation market. Despite its good recyclability, the willingness of PS recycling remains low, largely due to the high recycling cost and limited profitability. This review examines the research progresses, gaps, and challenges in areas that affect the recycling costs, including but not limited to logistics, packaging design, and policymaking. We critically evaluate the recent developments in upcycling strategies, and we particularly focus on tandem and hydrogen-atom transfer (HAT) upcycling strategies. We conclude that future upcycling studies should focus on not only reaction chemistry and mechanisms but also economic viability of the processes. The goal of this review is to stimulate the development of innovative recycling strategies with low recycling costs and high economic output values. We hope to stimulate the economic and technological momentum of PS recycling towards a sustainable and circular economy.
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Affiliation(s)
- Zhen Xu
- School of Chemistry and Chemical Engineering, Northwest Polytechnology University, Xi'an, 710000, China
- Department of Chemistry, Virginia Tech, Blacksburg, VA-24061, US
| | - Dongshi Sun
- School of Information and Business Management, Dalian Neusoft University of Information, Dalian, 116023, China
| | - Jianjun Xu
- Institute of Supply Chain Analytics, Dongbei University of Finance and Economics, Dalian, 116025, China
| | - Rong Yang
- School of Chemistry and Chemical Engineering, Northwest Polytechnology University, Xi'an, 710000, China
| | - Jennifer D Russell
- Department of Chemistry, Virginia Tech, Blacksburg, VA-24061, US
- Department of Sustainable Biomaterials, Virginia Tech, Blacksburg, VA-24061, US
| | - Guoliang Liu
- Department of Chemistry, Virginia Tech, Blacksburg, VA-24061, US
- Macromolecules Innovation Institute, Virginia Tech, Blacksburg, VA-24061, US
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6
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Rani S, Aslam S, Lal K, Noreen S, Alsader KAM, Hussain R, Shirinfar B, Ahmed N. Electrochemical C-H/C-C Bond Oxygenation: A Potential Technology for Plastic Depolymerization. CHEM REC 2024; 24:e202300331. [PMID: 38063812 DOI: 10.1002/tcr.202300331] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2023] [Revised: 11/23/2023] [Indexed: 03/10/2024]
Abstract
Herein, we provide eco-friendly and safely operated electrocatalytic methods for the selective oxidation directly or with water, air, light, metal catalyst or other mediators serving as the only oxygen supply. Heavy metals, stoichiometric chemical oxidants, or harsh conditions were drawbacks of earlier oxidative cleavage techniques. It has recently come to light that a crucial stage in the deconstruction of plastic waste and the utilization of biomass is the selective activation of inert C(sp3 )-C/H(sp3 ) bonds, which continues to be a significant obstacle in the chemical upcycling of resistant polyolefin waste. An appealing alternative to chemical oxidations using oxygen and catalysts is direct or indirect electrochemical conversion. An essential transition in the chemical and pharmaceutical industries is the electrochemical oxidation of C-H/C-C bonds. In this review, we discuss cutting-edge approaches to chemically recycle commercial plastics and feasible C-C/C-H bonds oxygenation routes for industrial scale-up.
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Affiliation(s)
- Sadia Rani
- Department of Chemistry, The Women University Multan, Multan, 60000, Pakistan
| | - Samina Aslam
- Department of Chemistry, The Women University Multan, Multan, 60000, Pakistan
| | - Kiran Lal
- Department of Chemistry, The Women University Multan, Multan, 60000, Pakistan
| | - Sobia Noreen
- Institute of Chemistry, University of Sargodha, Sargodha, 40100, Pakistan
| | | | - Riaz Hussain
- Department of Chemistry, University of Education Lahore, D.G. Khan Campus, 32200, Pakistan
| | - Bahareh Shirinfar
- West Herts College - University of Hertfordshire, Watford, WD17 3EZ, London, United Kingdom
| | - Nisar Ahmed
- School of Chemistry, Cardiff University, Main Building, Park Place, Cardiff, CF10 3AT, United Kingdom
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7
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Ran H, Zhang S, Ni W, Jing Y. Precise activation of C-C bonds for recycling and upcycling of plastics. Chem Sci 2024; 15:795-831. [PMID: 38239692 PMCID: PMC10793209 DOI: 10.1039/d3sc05701a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2023] [Accepted: 12/07/2023] [Indexed: 01/22/2024] Open
Abstract
The rapid accumulation of plastic waste has led to a severe environmental crisis and a noticeable imbalance between manufacturing and recycling. Fortunately, chemical upgradation of plastic waste holds substantial promise for addressing these challenges posed by white pollution. During plastic upcycling and recycling, the key challenge is to activate and cleave the inert C-C bonds in plastic waste. Therefore, this perspective delves deeper into the upcycling and recycling of polyolefins from the angle of C-C activation-cleavage. We illustrate the importance of C-C bond activation in polyolefin depolymerization and integrate molecular-level catalysis, active site modulation, reaction networks and mechanisms to achieve precise activation-cleavage of C-C bonds. Notably, we draw potential inspiration from the accumulated wisdom of related fields, such as C-C bond activation in lignin chemistry, alkane dehydrogenation chemistry, C-Cl bond activation in CVOC removal, and C-H bond activation, to influence the landscape of plastic degradation through cross-disciplinary perspectives. Consequently, this perspective offers better insights into existing catalytic technologies and unveils new prospects for future advancements in recycling and upcycling of plastic.
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Affiliation(s)
- Hongshun Ran
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University Nanjing 210023 China
- Institute for the Environment and Health, Nanjing University Suzhou Campus Suzhou 215163 China
| | - Shuo Zhang
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University Nanjing 210023 China
- Institute for the Environment and Health, Nanjing University Suzhou Campus Suzhou 215163 China
| | - Wenyi Ni
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University Nanjing 210023 China
- Institute for the Environment and Health, Nanjing University Suzhou Campus Suzhou 215163 China
| | - Yaxuan Jing
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University Nanjing 210023 China
- Institute for the Environment and Health, Nanjing University Suzhou Campus Suzhou 215163 China
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8
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Hsu JH, Ball TE, Oh S, Stache EE, Fors BP. Selective Electrocatalytic Degradation of Ether-Containing Polymers. Angew Chem Int Ed Engl 2024; 63:e202316578. [PMID: 38032347 DOI: 10.1002/anie.202316578] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2023] [Revised: 11/28/2023] [Accepted: 11/30/2023] [Indexed: 12/01/2023]
Abstract
Leveraging electrochemistry to degrade robust polymeric materials has the potential to impact society's growing issue of plastic waste. Herein, we develop an electrocatalytic oxidative degradation of polyethers and poly(vinyl ethers) via electrochemically mediated hydrogen atom transfer (HAT) followed by oxidative polymer degradation promoted by molecular oxygen. We investigated the selectivity and efficiency of this method, finding our conditions to be highly selective for polymers with hydridic, electron-rich C-H bonds. We leveraged this reactivity to degrade polyethers and poly(vinyl ethers) in the presence of polymethacrylates and polyacrylates with complete selectivity. Furthermore, this method made polyacrylates degradable by incorporation of ether units into the polymer backbone. We quantified degradation products, identifying up to 36 mol % of defined oxidation products, including acetic acid, formic acid, and acetaldehyde, and we extended this method to degrade a polyether-based polyurethane in a green solvent. This work demonstrates a facile, electrochemically-driven route to degrade polymers containing ether functionalities.
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Affiliation(s)
- Jesse H Hsu
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14850, USA
| | - Tyler E Ball
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14850, USA
| | - Sewon Oh
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14850, USA
| | - Erin E Stache
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14850, USA
- Department of Chemistry, Princeton University, Princeton, NJ 08544, USA
| | - Brett P Fors
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14850, USA
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9
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Zhang S, Findlater M. Electrochemically Driven Hydrogen Atom Transfer Catalysis: A Tool for C(sp 3)/Si-H Functionalization and Hydrofunctionalization of Alkenes. ACS Catal 2023; 13:8731-8751. [PMID: 37441236 PMCID: PMC10334887 DOI: 10.1021/acscatal.3c01221] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2023] [Revised: 05/27/2023] [Indexed: 07/15/2023]
Abstract
Electrochemically driven hydrogen atom transfer (HAT) catalysis provides a complementary approach for the transformation of redox-inactive substrates that would be inaccessible to conventional electron transfer (ET) catalysis. Moreover, electrochemically driven HAT catalysis could promote organic transformations with either hydrogen atom abstraction or donation as the key step. It provides a versatile and effective tool for the direct functionalization of C(sp3)-H/Si-H bonds and the hydrofunctionalization of alkenes. Despite these attractive properties, electrochemically driven HAT catalysis has been largely overlooked due to the lack of understanding of both the catalytic mechanism and how catalyst selection should occur. In this Review, we give an overview of the HAT catalysis applications in the direct C(sp3)-H/Si-H functionalization and hydrofunctionalization of alkenes. The mechanistic pathways, physical properties of the HAT mediators, and state-of-the-art examples are described and discussed.
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Affiliation(s)
- Sheng Zhang
- Institutes
of Physical Science and Information Technology, Key Laboratory of
Structure and Functional Regulation of Hybrid Materials of Ministry
of Education, Anhui University, Hefei, Anhui 230601, China
| | - Michael Findlater
- Department
of Chemistry and Biochemistry, University
of California Merced, Merced, California 95343, United States
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10
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Cribari MA, Unger MJ, Martell JD. A Horseradish Peroxidase-Mediator System for Benzylic C-H Activation. ACS Catal 2022; 12:12246-12252. [PMID: 37153120 PMCID: PMC10162642 DOI: 10.1021/acscatal.2c03424] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Enzyme-mediator systems generate radical intermediates that abstract hydrogen atoms under mild conditions. These systems have been employed extensively for alcohol oxidation, primarily in biomass degradation, but they are underexplored for direct activation of C(sp3)-H bonds in alkyl groups. Here, we combine horseradish peroxidase (HRP), H2O2, and redox mediator N-hydroxyphthalimide (NHPI) for C(sp3)-H functionalization of alkylbenzene-type substrates. The HRP-NHPI system is >10-fold more active than existing enzyme-mediator systems in converting alkylbenzenes to ketones and aldehydes under air, and it operates from 0-50 °C and in numerous aqueous-organic solvent mixtures. The benzylic substrate radical can be trapped through a reaction with NHPI, demonstrating the formation of benzylic products beyond ketones. Furthermore, we demonstrate a one-pot, two-step enzymatic cascade for converting alkylbenzenes to benzylic amines. Overall, the HRP-NHPI system enables the selective benzylic C-H functionalization of diverse substrates under mild conditions using a straightforward procedure.
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Affiliation(s)
- Mario A. Cribari
- Department of Chemistry, University of Wisconsin–Madison, Madison, WI, 53706, USA
| | - Maxwell J. Unger
- Department of Chemistry, University of Wisconsin–Madison, Madison, WI, 53706, USA
| | - Jeffrey D. Martell
- Department of Chemistry, University of Wisconsin–Madison, Madison, WI, 53706, USA
- Carbone Cancer Center, University of Wisconsin School of Medicine and Public Health, Madison, WI, 53703, USA
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11
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Oh S, Stache EE. Chemical Upcycling of Commercial Polystyrene via Catalyst-Controlled Photooxidation. J Am Chem Soc 2022; 144:5745-5749. [PMID: 35319868 DOI: 10.1021/jacs.2c01411] [Citation(s) in RCA: 56] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Chemical upcycling of polystyrene into targeted small molecules is desirable to reduce plastic pollution. Herein, we report the upcycling of polystyrene to benzoyl products, primarily benzoic acid, using a catalyst-controlled photooxidative degradation method. FeCl3 undergoes a homolytic cleavage upon irradiation with white light to generate a chlorine radical, abstracting an electron-rich hydrogen atom on the polymer backbone. Under the oxygen-rich environment, high MW polystyrene (>90 kg/mol) degrades down to <1 kg/mol and produces up to 23 mol % benzoyl products. A series of mechanistic studies showed that chlorine radicals promoted the degradation via hydrogen-atom abstraction. Commercial polystyrene degrades efficiently in our method, showing the compatibility of our system with polymer fillers. Finally, we demonstrated the potential of scaling up our approach in a photoflow process to convert gram quantities of PS to benzoic acid.
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Affiliation(s)
- Sewon Oh
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
| | - Erin E Stache
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
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